Yet the United States hardly noticed the sixth and final moon landing, being more focused on escalating Vietnam War bombing and the growing Watergate scandal.

Budget concerns had already forced NASA to cancel three more planned Apollo flights.

The astronauts returned a record 253 pounds of lunar rock and soil samples, and featured Apollo's third and longest series of jaunts using a four-wheeled rover.

The two also conducted an extensive scientific investigation of the moon on the surface and from lunar orbit. Schmitt, a Harvard-trained geologist, was NASA's first scientist-astronaut.

On December 14, mission commander Cernan followed Schmitt back inside Challenger, becoming the last person on the moon.

'We shall return'

Before he stepped off the lunar surface, Cernan commented, "We leave as we came, and God willing, as we shall return -- with peace, and in hope for all mankind."

Cernan and Schmitt then rejoined Ron Evans, piloting their command ship America in lunar orbit. Apollo 17 splashed down five days later southeast of the Samoan Islands in the Pacific Ocean.

Today Cernan chairs his own technology and marketing consulting firm in Houston. Schmitt, who served as a U.S. senator from New Mexico from 1977 to 1982, consults and speaks on lunar geology and the future of space exploration.

The pair will take part in a 30th anniversary event December 19 at Houston's Johnson Space Center. Evans died in 1990.

Although NASA continues to study returning people to the moon, the agency's long-term exploration plans are concentrating on Mars. China, however, has expressed interest in sending a crew to the moon, possibly within the next five years.